The invention is related to an adaptive control system for single-input single-output or multivariable time-variant processes with known or unknown parameters and with or without time delays. Such control systems are useful in many diverse fields such as aeronautics, electronics, chemical engineering, etc. Examples of processes in which the adaptive-predictive control system has been applied are single-input single-output control of an aircraft where the pitch angle is controlled by elevator position, and the multivariable control of a distillation column where top and bottom compositions are controlled by reflux and steam flow rates.
It is known that the control performance of a system with a control system based on constant parameters deteriorates when the dynamic parameters of the process vary in an unforeseen way which is not capable of direct or indirect measurement. In recent years, control techniques have been developed to try to solve this problem, the most noteworthy of which have been based on the model reference adaptive systems theory, which basically operates in one of the following ways: (1) performs a real time adaptive estimation of the parameters and state variables of the process, from which an adaptive regulator computes the control to be applied to the process, or (2) computes the control to be applied to the process through an adaptive control scheme in order to make the process output follow a model reference output. In general, in both of the above cases, the control structure requires the design of a corrector and the difficulties encountered in the computation of the parameters of this corrector as the order of the process increases, severely restricts the field of applications of these techniques.
The above considered techniques, as well as most of the adaptive or non-adaptive control techniques used so far in industry, are based in the traditional feedback methodology. According to this traditional methodology the control to be applied to the process is computed from the difference between a reference signal, which represents a desired value of the process output, and the process output. The present invention is able to overcome the above pointed out difficulties of known control techniques, acting in a way different from the traditional feedback methodology, and that is briefly described in the following.